Connecting device



June 2, 1964 K. KLINKwlTz coNNEc'rING DEVICE United States Patent O3,135,571 CQNNECTING DEVICE Kurt Klinkwitz, Berlin-Lubars, Germany,assigner to Robert Bosch Elektronik G.m.b.ll., Berlin-Wilmersdorf,Germany Filed .idly Z2, 1963, Ser. No. 296,740

Claims priority, application Germany Aug. 11, i962 27 Claims. (Cl.339-182) The present invention relates generally to the connector art,and, more particularly, to the construction of a coaxial plug forcoaxial high frequency cables, and especially antenna cables, having asleeve which surrounds the end of the cable, a plug prong in its frontend electrically connected with the inner conductor of the coaxialcable, and the sleeve being electrically connected with the outerconductor of the cable by means of contacts disposed on the outersurface of the sleeve.

Coaxial plugs are used when it is desired to connect the conductors of ahigh frequency cable in a detachable manner to a receiving device, suchas, for example, radio or television apparatus. usually does not haveany resilient elements and can be connected to the inner conductor ofthe cable without difficulty because the plug prong and the innerconductor are disposed centrally of the other elements and/or coaxially,substantial difficulties arise in the attempt to provide a satisfactoryand flawless electrical connection between the contacts positioned onthe outer surface of the sleeve and the outer conductor of the cable.For example, the outer conductor is provided in the form of a shieldingmesh disposed around the insulation of the inner conductor and most ofthe time is insulated by means of an outer shell or sheath. Specialconsiderations are required if, in addition, there is a necessity forfashioning the contacts on the outer surface of the sleeve to beresilient for purposes of contact safety and to obtain as small aphysical dimension of the plug as is possible.

Coaxial plugs are already known which have a metal sleeve whose rearwardend presses upon the outer conductor and establishes contact therewith.The front end f the sleeve carries an insulating ring for mounting theplug prong. With this construction there is the disadvantage that theinsulating distance between the sleeve and the prong of the plug isrelatively small since the circumference of the insulating ring issurrounded or enclosed by the sleeve. Furthermore, the sleeve sits uponthe outer conductor only by means of pressure and does not provide asafe contact between the outer conductor and the sleeve since the outerconductor is only disposed upon the relatively resilient insulation ofthe inner conductor.

ln another plug which is known the electrical contact between the outerconductor and the metal sleeve is provided by inserting hairpin-likecontact springs having one leg disposed between the outer conductor andthe insulating outer shell and with the other leg between the outersurface of the outer shell and the inner surface of the sleeve. Howeverthis construction also does not provide for the safe and proper makingof contact since the insulation of the inner conductor disposed beneaththe outer conductor yields and thus a firm contact is not provided.

ln order to obtain a faultless and proper contact at the other contactpoint which is involved only after the coaxial plug has been insertedinto the correspondingly shaped socket provided at the receiver andwhich contact point is disposed between the sleeve and the inner wall ofthe socket, a partially ring-shaped contact spring is provided in thefront portion of the above-described known plug and is positioned in anaxially parallel manner and is disposed against the inner wall of themetal sleeve.

While the plug prong The ends of this spring are bent radially outwardlyand project through longitudinal slits in the sleeve so as to extendexternally thereof and provide a resilient contact with the socket ofthe receiving device. However, the manufacture of this partiallyring-shaped contact spring is very expensive because the manufacturingtolerances must be maintained within very small limits.

Another known type of plug is constructed according to GermanGebrauchsmuster No. 1,837,970. In this construction, a sleeve moldedfrom plastic material surrounds the end of a coaxial cable. The prong ofthe plug which is connected with the inner conductor passes through theforward end of the sleeve and two resilient sheet metal strips areprovided on the outer surface of the sleeve. The ends of these metalstrips are bent at right angles and inwardly toward the cable and arepressed into the cable shell by means of a pressure ring. These ends ofthe sheet metal strips are formed as teeth on the front faces thereofand these teeth puncture the shell of the cable and establish contactwith the outer conductor which is provided immediately beneath theshell. However, the Contact between the sheet metal strips and the outerconductor is not reliable because, in order to avoid damaging the outerconductor the contact pressure may only be very small and because thecounter pressure is only provided by the Very resilient insulationbetween the outer conductor and the inner conductor. The two resilientsheet metal strips engage each other at their forward ends and the plugprong passes therethrough and is spaced at a small distance therefrom.The insulating distance between theplug prong and the two resilientsheet metal strips can only be maintained to be suiciently great at thecost of the over-all structural length of the plug.

With these defects of the prior art in mind, it is a main object of thepresent invention to provide a plug construction for coaxial cableswhich assures the making of a secure contact at the outer conductor.

Another object of the invention is to provide a plug of the characterdescribed wherein the insulating distance at the point that the plugprong penetrates through the plug is suiciently large so as to avoid thedefects of the prior art.

A further object of the present invention is to provide a plugconstruction which accomplishes the above-mentioned objects and at lowmanufacturing costs.

Still another object of the invention is to provide a plug constructionfor coaxial cables wherein the contacts for the outer conductor may besecurely connected to the outer conductor and pass through the plug bodyoutwardly thereof.

These objects and'others ancillary thereto are accomplished inaccordance with preferred embodiments of the invention wherein a sleeveforming the plug body is a plastic body which is extruded or moldeddirectly about the end of the cable and the plug prong. Contacts areconnected with the outer conductor and they are in the form of leafsprings which are soldered to the outer conductor, penetrate outwardlythrough the plastic body, and are bent backwardly toward the outersurface of the plastic body.

The above-mentioned known plugs and others are constructed in such amanner that a connection can not be provided by soldering the outerconductor and a sleeve of metal and/or the contacts provided on theouter surface of a sleeve molded from plastic. In accordance with thepresent invention the contacts are arranged in the form of leaf springsand are directly soldered onto the outer conductor and pass through theplastic body exteriorly thereof. Furthermore, because the location ofthe leaf spring penetration through the plastic body is disposed at anappreciable distance from the location where the plug prong passesoutwardly of the plastic body, the insulating distance between the plugprong and the leaf springs is sufliciently long, and the plug can bemanufactured in a simple manner.

Additional objects and advantages of the present invention will becomeapparent upon consideration of the following description when taken inconjunction with the accompanying drawings in which:

FIGURE l is a sectional View, partly in elevation, of a straight coaxialplug in accordance with the present invention.

FIGURE 2 is an elevational view of an angle plug.

FIGURE 3 is a sectional view, partly in elevation, of another form ofangle plug.

In accordance with the present invention a particularly secureconnection of the leaf-spring-type contacts with the outer conductor isprovided by soldering the leaf springs to the outer conductor. This isaccomplished by forming the leaf springs as projections or extensions ona cylindrical ring which surrounds the outer conductor. If the outerconductor is, for example, a shielding mesh, then a ring may be slippedover the mesh and can be soldered thereto in a simple and trouble-freemanner. The leaf springs may project from the front surface of thecylindrical ring, considered in the direction of the axis of the ring,and they are bent to extend radially away from the ring. These leafsprings penetrate the plastic body in the direction in which theyproject and finally, those portions thereof which project out of theplastic body are bent backwards toward the outer surface of this plasticbody. Mechanical stresses on the portions of the leaf springs whichproject out of the plastic body can not be transferred or transmitted tothe soldered joint because the leaf springs are fixedly embedded in theplastic body. In a suitable manner, the plug prong may be anchored inthe plastic body by providing a collar at the rearward end of the plugprong and the plastic. body extends around this collar.

According to a further feature of the invention an insert may beprovided in the cable, at least in the region of the plastic body andthis insert may, for example, be a Wire or band-shaped element whichprovides rigidity. The insert is used in order to prevent thehigh-frequency cable, which usually is flexible, from assuming anundesirable position during the extruding process and/or during themolding process wherein the outer conductor may be positioned too closeto the outer surface of the extruded plastic body. This is simpler thanthe construction which is provided in a known plug wherein supportingelements, together with supporting rings spaced at a distance from oneanother, are provided which maintain the cable in a central position andwhich are sprayed with plastic or molded together with the cable.

Preferably, in the event that low-loss coaxial high frequency cables areused wherein the inner conductor is mounted within a hollow tube and hasa substantially larger free cross section than the cross section of theinner conductor, an insert for providing rigidity may be inserted in thehollow tube surrounding the inner conductor. In accordance with furtherfeatures of the invention this stiffening or rigidifying insert mayextend beyond the rearward end of the plastic body and either over itsentire length or at certain sections along its length it may bepermanently flexible, and, for example, may be angularly bent at rightangles at a point behind the plastic body.

The plug may be thus produced in its nished form with an insert which isdisposed axially of the plug and subsequently, if necessary, the portionof the cable which projects from the rearward end of the plastic bodymay be bent into any direction as is desired or necessary under theexigencies of the situation. Also, the plug may be used withoutangularly bending the cable at all, for example, in order to be able tohandle the plug more conveniently.

A corresponding strong copper wire has proven to be advantageous as aninsert, and such a wire may be more fiexible in the longitudinal portionthereof which extends beyond the rearward end of the plastic body thanin the region of the plastic body. This may be provided, such as, by notannealing the wire in the region of the plastic body.

The construction of a plug in accordance with the present inventionprovides a substantial decrease in expense in comparison with thepreviously known plugs and assures a secure contact at the outerconductor even if the construction providing the possibility for bendingof the cable into the desired position when needed is not used, butrather if coaxial plugs having an axially bent cable, which are calledangle plugs, are delivered directly from the plant. Furthermore, anangle plug which is constructed in accordance with the present inventionhas substantially smaller dimensions than those angle plugs which havebeen known heretofore and they generally satisfy the requirements forsuch angle plugs.

Furthermore, for sturdier consultations of such angle plugs thestifening insert and the plastic body may have an angular, for example,a right-angle bend. The stiifening or reinforcing insert also extends inthe region of the plastic body and has a corresponding bend so that thecorrect position of the cable within the body is guaranteed even afterthe molding process. The reinforcing insert does not extend beyond therearward end of the plastic body. The plastic body extends over thelength of the bend and provides a sturdier construction to the plug thanthat of the above-mentioned angle plug in which the plastic body extendsonly over the forward straight portion of the insert.

In accordance with another feature of the present invention, the plugprong may be hollow and the rigidifying insert may extend into thehollow chamber of the plug prong and if desired may be soldered to theplug prong. Because of this construction the plug prong is provided witha particularly secure mounting in the plastic body since the reinforcinginsert primarily extends within the cable and this cable in turn islixedly embedded in the plastic body.

In order to provide contact between the inner conductor of the cable andthe plug prong, the inner conductor extends into the hollow cavity ofthe plug prong and is soldered to the prong. The soldering operation isshortened and simplified if the rigidifying insert as well as the innerconductor extend up to the forward end of the hollow plug prong and ifthe plug prong, the insert and the inner conductor are soldered togetherwith a single soldering operation.

Another arrangement for the electrical connection between the innerconductor and the plug prong is provided by soldering the innerconductor to the stiifening insert close to the rearward portion of theinsert. The front end of the rigidifying insert is then soldered to thefront end of the hollow plug prong.

In accordance with a further feature of the invention a plug may beconstructed by soldering onto the outer conductor of a cable a generallycylindrical ring having radially outwardly extending leaf springs. Theleaf springs are disposed substantially at right angles to the centralaxis of the ring and a plug prong is electrically connected to an innerconductor, for example, by soldering. The pastic body is provided aboutthe cable using a die mold and the plastic body encloses the end of thecable together with the ring and the end of the plug prong. Portions ofthe leaf springs project outwardly of the plastic body and are bentbackwardly toward the outer surface of this plastic body. After theplastic body has been produced, the leaf springs may be bent backwardlytoward the outer surface of the plastic body in such a manner that theylie on the outer surface of the body in a somewhat arched fashion,approximately like the leaf springs of a banana plug and by this meansthe making of proper contact is particularly assured. The

extrusion and/ or molding die may be constructed so that the greaterpart of the length of the plug prong, the leaf springs extending atright angles to the central axis of the ring, and the rearwardlyextending cable can be accommodated by the walls of the die. If astronger cable is to be provided with a plug, the cable, only to a minordegree, will be capable of being pushed away from its original positionduring extruding, particularly since it is securely centered at itsfront end by means of the leaf springs.

However, in most cases, such as for example, in the case of an antennacable used for a vehicle antenna or for television apparatus, arelatively thin and exible cable is provided with a plug. In order toassure that such a cable maintains its position during the moldingprocess a suitable stitfening insert may be mounted within the cable andsoldered together with the inner conductor as well as with the plugprong.

ln order to provide the electrical connection between the innerconductor and the plug prong the inner conductor is arranged to at firstproject outwardly of the front end of the cable. The inner conductor isthen soldered near the rearward end of the stiffening insert and thehollow plug prong is placed onto the front end of the insert and issoldered to the insert. The insert is pushed so far into the hollow tubewhich surrotmds the inner conductor that the rearward end of the plugprong touches or abuts against the front end of the cable. The ring isthen soldered onto the outer conductor and the plastic body molded ontothe end of the cable and about the ring with the leaf springs extendingoutwardly therefrom. Finally, the leaf springs are bent rearwardlytoward the outer surface of the plastic body.

According to a further feature of the present invention the electricalconnection between the inner conductor and the plug prong can also beprovided by placing the hollow plug prong over the front of thestiffening insert and over the inner conductor and by soldering theinsert as well as the inner conductor to the front end of the plugprong.

By means of the above-described methods, straight plugs can be made whenthe cable exits from the rearward end of the plastic body in a straightline along the center longitudinal axis of the plugs. In many cases itis desirable that the cable exit from the plug at a particular angle andpreferably at a right angle. In order to provide such an angle plug thestitfening insert may be made of permanently exible material which isconsiderably longer than the distance from the front end of the plugprong to the rearward end of the plastic body. After the electricalconnection has been made between the inner conductor and the plug prong,the insert is placed into the cable far enough so that it projects anappreciable distance beyond the end of the plastic body. After theplastic body has been molded to the end of the cable, the portion of thecable projecting from the rearward end of the plastic body is bent tothe desired angle immediately behind the plastic body.

According to a further feature of the invention a sturdier angle plugcan be made by placing the insert in the cable while it is straight.Then, the insert is bent angularly together with the cable and theplastic body is formed in a die mold with the correspondingly bentcentral or longitudinal axis.

With more particular reference to the drawings, FIG- URE l illustratesone embodiment of a coaxial plug in accordance with the presentinvention. A coaxial cable i arranged to carry high frequencies has aninner conductor 3 which extends in an undulating manner within aninsulating hollow tube 2. An outer conductor 3 is provided in the formof a shielding mesh, and an insulating outer shell 4 is provided overthis mesh. A stiifening or reinforcing insert 9 of conductive materialis inserted into the end of the cable. The left end of the insert 9 iselectrically connected with the hollow plug prong 7 by means of asoldered connection 25. At its right end 6 the insert is electricallyconnected with the inner conductor 8 also by means of a solderedconnection 1S.

A cylindrical ring 6 is soldered onto the shielding mesh 3. The ring hastwo projections which originally are disposed at right angles to thecentral axis of the ring as illustrated in dashed lines. Theseprojections are constructed in the form of leaf springs 5.

A plastic body 1Q is directly molded around the cable 1 and the plugprong 7. This plastic body xedly and immovably mounts the plug prong '7to the cable by means of a collar lr6 provided thereon as well as thetwo leaf springs 5 which are then bent back against the outer side ofthe plastic body 10 as illustrated in solid lines in FIG- URE l.

With more particular reference now to FIGURE 2, a modification of thepresent invention is illustrated wherein a cable 22 at first has astraight end as indicated by the dashed lines. A straight insert 12 isprovided in the cable and the insert together with the inner conductor1'7 is provided within a hollow tube 21 of the cable 22. The insert andthe inner conductor are soldered to the left end of a hollow plug prong7 by means of a conventional soldering joint 11. A plastic body 13 ismolded about the straight insert 12. The cable 22 projects out of thebody in the direction shown in dashed lines and toward the right so thata straight plug is formed. The leaf springs 5 are placed into theposition illustrated in the drawing. After the cable has been bentangularly directly behind the plastic body, the straight insert 12becomes an insert which is angled downwardly as shown at 19 and a bentcable 26 is thus formed. Thus, the plug which is shown in solid lines inFIGURE 2 is an angle plug which has been bent into this form from astraight plug.

With more particular reference to FIGURE 3, a further embodiment of thepresent invention is illustrated. A cable 23 is provided with an insert14 which is initially straight and which is soldered to the left end ofa plug prong 7 together with the forward end or leading end of an innerconductor 2t) by means of a soldered joint 24. The cable is then bent ata right angle downwardly together with its insert and while bent it isplaced into a die mold having a central axis which runs to be coincidentwith the bend and a plastic body 15 is thus molded. The leaf springs 5which initially project from the plastic body at right angles theretoare then bent into the form as illustrated in the drawing.

It will be understood that the above description of the `presentinvention is susceptible to various modifications,

changes and adaptations, and the same are intended to be comprehendedwithin the meaning and range of equivalents of the appended claims.

What is claimed is:

1. A coaxial plug for coaxial cables having inner and outer conductors,said plug comprising, in combination: a plug prong electricallyconnected with the inner conductor of a cable; a one-piece sleeve-likeplastic body directly surrounding the end of such cable and a portion ofthe plug prong for supporting the prong; and contacts in the form ofleaf springs in electrical contact with the outer conductor of suchcable, said leaf springs penetrating externally of said plastic body andbeing bent backwardly toward the outer surface of said body.

2. In a coaxial plug for coaxial high frequency cables, and especiallyantenna cables, having a sleeve enclosing the end of the cable and atits front end carrying a plug prong electrically connected with theinner conductor of the cable, the sleeve having contacts on its outersurface which are electrically connected with the outer conductor of thecable, the improvement wherein the sleeve is a plastic body moldeddirectly around the cable and the plug prong, the contacts connectedwith the outer conductor are leaf springs soldered to the outerconductor, said leaf springs penetrating the plastic body and being bentbackwardly toward the outer surface of the body.

3. The improvement as defined in claim 2 comprising a ring surroundingthe outer conductor, and said leaf springs being defined by projectionson said ring. a

4. The improvement as defined in claim 2 wherein said plug prong has acollar in proximity to its rearward end, and said plastic body extendingaround and holding said collar.

5. The improvement as defined in claim 2 comprising a stiffening insertin the cable at least in the region of said plastic body.

6. The improvement as defined in claim 5 wherein said insert extendsbeyond the rearward end of said body.

7. The improvement as defined in claim 5 wherein said insert ispermanently fiexible at least along portions of its length.

8. The improvement as defined in claim 5 wherein said insert is bentangularly behind said plastic body.

9. The improvement as defined in claim 8 wherein the insert is bentsubstantially at a right angle.

10. The improvement as defined in claim 5 wherein both said insert andsaid body are bent angularly.

11. The improvement as defined in claim 10 wherein said insert and bodyare bent at substantially a right angle.

12. The improvement as defined in claim 5 wherein the plug prong ishollow and the insert extends into the interior of the prong.

13. The improvement as defined in claim 12 wherein the insert issoldered to the prong.

14. The improvement as dened in claim 13 wherein the inner conductor isdisposed within the prong and is soldered to the prong.

15. The improvement as defined in claim 13 wherein the inner conductoris soldered to the insert.

16. The improvement as defined in claim 15 wherein the inner conductoris soldered to the insert in proximity to the rearward end of theinsert.

17. A method for making coaxial plugs for coaxial cables including aninner conductor, an insulating hollow tube, and an outer conductor,comprising the steps of: soldering onto the outer conductor of a cable aring having leaf springs disposed substantially at right angles to thecentral axis of the ring; electrically connecting a plug prong with theinner conductor of such cable; molding in a die mold a plastic body toenclose the end of the cable, a portion of the plug prong, and the ringso that the leaf springs project therefrom; and bending the projectingportions of the leaf springs backwardly toward the outer surface of theplastic body.

18. A method as defined in claim 17 wherein the electrically connectingstep is accomplished by soldering.

19. A method as defined in claim 17 comprising placing a stiffeninginsert into the cable and soldering it with the inner conductor and withthe plug prong to accomplish the electrically connecting step.

20. A method as defined in claim 17 wherein the step of electricallyconnecting the prong and the inner conductor includes removing portionsof the hollow tube and the outer conductor so that the inner conductorprojects from the forward end of the cable, soldering the projectinginner conductor to a stiffening insert in proximity to its rearward end,placing the plug prong which is hollow onto the front end of the insertand soldering it thereto, and pushing the insert into the hollow tubeuntil the rearward end of the plug prong abuts against the front end ofthe cable.

21. A method as defined in claim 17 wherein the step i 0f electricallyconnecting the prong and the inner conductor includes pushing astiffening insert into the hollow tube, placing the plug prong which ishollow over the insert `and the inner conductor, and soldering theinsert and the inner conductor to the front end of the plug prong.

22. A method for making coaxial plugs for coaxial cables including aninner conductor, an insulating hollow tube, and an outer conductor,comprising the steps of: placing into the cable a stiffening insert ofpermanently flexible material and which is a considerable distancelonger lthan the distance from the front end of the prong to theintended rearward end of the plug until it projects a considerabledistance beyond the point where the rearward end Iof the plug is to belocated; soldering onto the outer conductor of a cable a ring havingleaf springs disposed substantially at right angles to the central axisof the ring; electrically connecting the plug prong with the innerconductor of such cable; molding a plastic body to enclose the end ofthe cable, a portion of the plug prong, and the ring so that the leaftsprings project therefrom; bending the projecting portions of the leafsprings backwardly toward the outer surface of the plastic body; andbending the cable immediately behind the plastic body so it is disposedangularly with respect to the body.

23. A method as defined in claim 22 wherein the step of electricallyconnecting the plug with the inner conductor includes soldering theinner conductor to the rearward end of the insert, and soldering thefront end of the insert to the plug prong.

24. A method as defined in claim 22 wherein the step of electricallyconnecting the plug with the inner conductor includes soldering both theinner conductor and the insert to the plug prong.

25. A method for making coaxial plugs for coaxial cables including aninner conductor, an insulating hollow tube, and an outer conductor,comprising the steps of: placing a straight stiiiening insert into thecable; soldering onto the outer conductor of a cable a ring having leafsprings disposed substantially at right angles to the central axis ofthe ring; electically connecting a plug prong with the inner conductorof such cable; bending the cable and the insert to substantially form aright angle; molding a plastic body to enclose the end of the cable, aportion of the plug prong, and the ring so that the leaf springs projecttherefrom and the body forms a right angle; and bending the projectingportions of the leaf springs backwardly toward the outer surface of theplastic body.

26. A method as defined in claim 25 wherein the step of electricallyconnecting the plug with the inner conductor includes soldering theinner conductor to the rearward end of the insert, and soldering thefront end of the insert to the plug prong.

27. A method as defined in claim 25 wherein the step of electricallyconnecting the plug with the inner conductor includes soldering both theinner conductor and the insert to the plug prong.

References Cited in the file of this patent UNITED STATES PATENTS1,175,343 Conard Mar. 14, 1916 3,001,169 Blonder Sept. 19, 1961 FOREIGNPATENTS 531,947 Great Britain Ian. 14, 1941 677,580 Great Britain Aug.20, 1952

1. A COAXIAL PLUG FOR COAXIAL CABLES HAVING INNER AND OUTER CONDUCTORS,SAID PLUG COMPRISING, IN COMBINATION: A PLUG PRONG ELECTRICALLYCONNECTED WITH THE INNER CONDUCTOR OF A CABLE; A ONE-PIECE SLEEVE-LIKEPLASTIC BODY DIRECTLY SURROUNDING THE END OF SUCH CABLE AND A PORTION OFTHE PLUG PRONG FOR SUPPORTING THE PRONG; AND CONTACTS IN THE FORM OFLEAF SPRINGS IN ELECTRICAL CONTACT WITH THE OUTER CONDUCTOR OF SUCHCABLE, SAID LEAF SPRINGS PENETRATING EXTERNALLY OF SAID PLASTIC BODY ANDBEING BENT BACKWARDLY TOWARD THE OUTER SURFACE OF SAID BODY.